Minor Flood
-30 ft
Current Water Level
Gage Height
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Streamflow
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Last Reading
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This is an NWS forecast point (LID: MCCI2). Live data may be limited. View on NWS AHPS →
FLOOD STAGES
Know the flood categories.
Flood stages defined by the National Weather Service. Gage height data from USGS Water Resources.
Action Stage
-100 ft
What Floods at Each Level
-22 ft
Lowest rim of McCook Reservoir.
-40 ft
McCook Reservoir reaches 100 percent of full storage. Combined sewer overflow event likely in central Cook County. Water remains contained within the reservoir.
-95 ft
McCook Reservoir reaches 75 percent of full storage. Combined sewer overflow event possible in central Cook County.
-155 ft
McCook Reservoir reaches 50 percent of full storage.
-215 ft
McCook Reservoir reaches 25 percent of full storage.
-280 ft
McCook Reservoir is empty, 0 percent of full storage.
Impact statements from the National Weather Service, describing what typically happens at each water level.
7-Day Water Level Chart
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Historic Crests
| Date | Stage | Flow |
|---|---|---|
| Apr 15, 2026 | -33.7 ft | — |
| Apr 4, 2026 | -35 ft | — |
| May 5, 2019 | -35.4 ft | — |
About This Gauge
NWS LID
MCCI2
River
Mainstream Deep Tunnel
County
Cook, IL
Coordinates
41.7775°N, 87.8366°W
Get Flood Alerts for Mainstream Deep Tunnel
StormCast monitors this gauge and sends a push notification to your phone when the water level crosses into a new flood category — even at 3 AM.
Frequently Asked Questions
What is the current water level of Mainstream Deep Tunnel at McCook Reservoir?
The Mainstream Deep Tunnel at McCook Reservoir gauge is maintained by USGS and reports water levels every 15 minutes. Visit this page to see the latest reading updated live, or download StormCast to get push alerts when levels rise.
What is flood stage for Mainstream Deep Tunnel at McCook Reservoir?
The NWS-defined flood stage for Mainstream Deep Tunnel at McCook Reservoir is -30 feet. Action stage begins at -100 feet. Moderate flooding starts at N/A feet, and major flooding at N/A feet.
How do I get alerts when Mainstream Deep Tunnel rises?
Download StormCast free on Google Play, go to River Gauges, and add Mainstream Deep Tunnel at McCook Reservoir to your watchlist. StormCast will send a push notification to your phone whenever the water level crosses into a new NWS flood category.
Where is the Mainstream Deep Tunnel at McCook Reservoir gauge located?
The gauge is located in Cook County, Illinois at coordinates 41.7775°N, 87.8366°W. Data is provided by the U.S. Geological Survey and the National Weather Service.
On This River
Downstream: Chicago Sanitary and Ship Canal at Lemont
More Resources
Source & Notes
Data provided by: MWRD
- River forecasts for this location take into account past and future precipitation. The stages/flows that will occur may be different if future rainfall is different than forecast.